Commonly Used Computer Terms


Physical components of the computer system which can be touched or seen are known as hardware e.g. Monitor, keyboard, mouse, chips, wires, buses etc.


It cannot be touched or seen and are instructions, programs or software. It controls and manages hardware resources for optimum use. They are of two types System Software and Application Software. E.g. Word Application Package, Operating Systems Software etc.


It is software substituted for hardware and stored in read-only memory. i.e. ROM used as BIOS to check proper functioning of computer components.


It is raw facts like numbers, characters etc.  For e.g. Number of items sold is data, as it is a number.


Information is processed or manipulated data. For e.g. which product sells more in a week.

Input Unit

Data and instructions from the user are given by this unit. It converts human understandable characters to binary code which is understood by computer. It consists of keyboard, mouse etc.

Output Unit

Processed data is given to the user by this unit. It converts computer given signals to human understandable characters. It consists of printer, monitor etc.

Storage Unit

All the data to be processed and instructions required for processing are stored in it. It also stores the intermediate and final results of processing before the results are released to output device.

Central Processing Unit

It is the brain of the system and has control unit and arithmetic logical unit.

Arithmetic Logical Unit

It executes arithmetic (addition, division etc.)  and logical (less than, equals, etc.) instructions.

Control Unit

It maintains order and directs the operation of the entire system by selecting, interpreting and

seeing to the execution of program instruction. It controls the flow of information in the computer.

Parallel and Serial Devices

In serial devices, only one element of data is sent at a time. Serial communications can have only two states: on or off.

To speed things up, we can add more wires. This allows simultaneous transmission of signals as in parallel. In PC, we often string eight wires in a parallel set, allowing eight bits to be sent at once.

Computer Bus

It is an electrical pathway through which the processor communicates with the internal and external devices attached to the computer.  It transfers data and instructions between the computer subsystems and processor. It also connects computer components to main memory and CPU.

It is also known as the data bus, address bus or the local bus.  Its size determines that how much data can be transferred at a time.  It has clock speed, measured in the MHz to synchronize all its operations.  Buses can be parallel and serial. There are different types of the buses which are

Data Bus – It carries the data between the different components of the computer.

Address Bus – It selects the route that has to be followed by the data bus to transfer the data.

Control Bus – It decides that whether the data should be written or read from the data bus.

Expansion Bus – It is used to connect the computer’s peripheral devices such as printer, modem and scanner with the processor.

Computer architecture

It is defined as the science and art of selecting and interconnecting hardware components to create computers that meet functional, performance and cost goals.

It forms a blueprint and functional description of requirements and design implementations for the various parts of a computer, focusing largely on the way by which the central processing unit (CPU) performs internally and accesses addresses in memory.

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